I placed a stainless steel idli stand in a pressure cooker (unsure if the cooker is Aluminium or steel, but it has the word "wrought" etched on its worn out bottom), poured some water into the cooker (the water was pre-boiled in a stainless steel saucepan on an induction cooker) and steamed some idlis. After steaming, I see this dark something at the bottom of the cooker, everywhere except where the idli stand was placed (the lighter coloured circle).
This is what the idli stand looks like:
And this is what the pressure cooker looks like:
- Did the stain (or perhaps it's not a stain. Perhaps it's a layer that got eroded) get created as a result of the reaction with the metals and water? What causes it? There's also a very thin white layer that gets created on the portion of the idli stand which is immersed in water.
- How do I get rid of the discolouration? Already tried using a liquid dishwashing agent. Didn't work. Tried a bit of vinegar and baking soda too. No use.
- Is it safe to cook using the pressure cooker, in its current state?
From a few searches, it could be:
- Chromium rust (but it couldn't be the same as in my case).
- Water deposits. Could perhaps be removed by vinegar or baking soda.
When I float an Aluminium container on the water in the pressure cooker, a white layer develops on the container. The white layer had also developed on the portion of the idli stand that was immersed in water. Am assuming it's some minerals dissolved in the water.